Electromagnetic structure



G. NAHMAN ELECTROMAGNETIC STRUCTURE `I uly 25, 1950 2 Sheets-Sheet l 1:1.4 Tli.

Filed DSC. 14, 1944 INVENTOR GasavejVa/z/vwn ATTORNEYS `July 25, 1950 G. NAHMAN ELECTROMAGNETIC STRUCTURE 2 Sheets-Sheet 2 Filed Dec. 14, 1944 ATTORNEYS Patented July 25, 1950 UNITED STATES PATENT OFFICE ELECTROMAGNETIC STRUCTURE Gustave Nahman, Englewood, N. J.

Application December 14, 1944, Serial No. 568,098

1 Claim. 1

The present invention relates to electro-magnetic frames, fields, cores and the like of the type used in electric transformers, motors, relays, switches, and other electro-magnetic devices.

While laminated cylindrical iron structures theoretically provide the most efficient magneto-- motive circuits, their use has imposed obstacles due to the cost and difficulty of assembling the required multiplicity of such laminations radially of the cylinder, bearing in mind that progressively greater thickness of laminations is required `from the core to the periphery. This difculty of assembly accounts to considerable extent for the use by the art of rectangular magnetic structures, since the laminations may thus be easily assembled in superposed relation.

It is an object of the present invention to prom vide a simple, expeditious and inexpensive procedure for assembling laminations of uniform thickness in generally radial relation for producing a cylindrical magnetic structure that combines the advantages of such cylindrical form with the economy of assembly heretofore attained only by the use of rectangular structures.

Another object is to provide a magnetic core structure made up of laminations in which magnetic material is present throughout the volume ofthe structure so that the reluctance is low with the elimination of the multiplicity of minor empty gaps that otherwise occur.

In the accompanying drawings, in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. l is a view in transverse cross-section of one embodiment of the generally sector shaped sub-assembly components of the cylindrical structure,

Figs. 2, 3, 4 and 5 are views similar to Fig. 1 of other embodiments thereof,

Fig. 6 is a plan view showing one embodiment of composite strip and illustrating the sub-division thereof into the laminated sub-assembly of the magnetic structure,

Figs. 7 and 8 are alternative embodiments thereof,

Fig. 9 is a perspective view showing the method of stamping the laminations from a sheet and the method of collecting the same,

Fig. 10 is a perspective view of the sectional holding band for the laminated sectors,

Fig. 11 is a view in longitudinal cross-section showing the apparatus for and method of assembly of the magnetic structure, and

Fig. 12 is a view in longitudinal cross-section ris-21) showing the impregnation of the assembly with magnetic plastic material.

Referring now to the drawings, there is shown in Fig. 1 a fragmentary view of a generally cylindrical magnetic structure made up of sector shaped sub-assemblies. Each sub-assembly is illustratively shown as having three laminations of uniform thickness all extending inward from the outer periphery of the structure and of progressively stepped radial length, lamination l5 extending to the inner hollow core, lamination l1 being somewhat shorter and lamination I8 being the shortest. Accordingly there is but a single lamination for each sector at the core, a double lamination at the mid section and a triple lamination at the outer periphery. The laminations are held together by spot soldering I9 in the embodiment of Fig. 1.

The sector sub-assembly in the embodiment of Fig. 2 is similar to that of Fig. l, except that magnetic rivets 20, preferably flush with the outer faces of the sub-assembly serve to clamp the parts together in an assembled relation.

The sub-assembly embodiment of Fig. 3 involves but two laminations, the longer lamination 2| having a reversely bent outer edge turned in as at 22, firmly to clamp the shorter lamination 23 in place, so that a triple stepped laminated structure is obtained, similar to that of Figs. 1 and 2, but without the use of solder or rivet fastening means.

In the embodiment of Fig. 4, two types of sector-shaped sub-assemblies are disposed in alternate relation; one set 24 is of the three-ply type of either Figs. 1, 2 and 3, illustratively shown as of the type of Fig. 2, and the intervening set 25 is of the two-ply type. However, the stepped side of set 25 faces the stepped side of a threeply set 24 and the steps of such two sets interfit as shown. The longer ply 26 of the two-ply set is of length intermediate the two longer plies 21 and 28 of the three-ply set and in face-to-face contact with the longest ply 21 of the adjacent three-ply section. A similar relation exists with respect to the shorter ply of set 25 and the associated plies of said set 24. It will thus be seen that the air-gaps between laminations of the wider sector made up of three of the sub-'assemblies, including two three-ply and one two-ply element are relatively small.

In the embodiment of Fig. 5, the plies are compressed for bevel shaped inner edges at 30 which arrangement also contributes to closer contiguity of the sub-assemblies and reduces the empty space therebetween. Preferably the bevel arrangement of Fig. 5 is used in each of the embodiments of Figs. 1, 2, 3 and 4 as its use there reduces the size of the gaps which are shown exaggerated in size.

In Figs. 6, 7 and 8 is shown an elongated strip of metal 3| which may be oi any of the embodiments previously described, stepped for maximum thickness at longitudinal edge 32 and for single ply at theopposite longitudinal edge. Of course each lamination of the strip is 'coated with suitable insulating varnish on one face. Strip 3| is to be stamped into individual rectangular subassemblies each to have material removed therefrom by stamping preferably a rectangular blank therefrom to afford an opening or gap for the electro-magnetic coil to be associated With the magnetic structure.

In the embodiment of Fig. 6, the rectangular gap 33 formed by saidblanking operation is in the interior; in Fig. 7 it is shown at 3st at one transverse edge 35 of the segment, and in Fig. 8 at 36 at the outer or thicker longitudinal edge thereof.

Desirably, the stamping is effected as shown in Fig.- 9 by feeding the strip along the bed S6 ci a punchpress, the punch P4 of which effects the removal of the rectangular blanks in each sequence, and is immediately followed in operation ofl punch P which severs the sub-assemblies. In order to collect the sub-assemblies thus formed, in arrangement'convenient for assembling them into the generally cylindrical magnet structure to be' built therefrom, the punch P feeds the sub-assemblies into a chute 38, to which is' removably attached the channel-shaped flexibly linked band i0 shown inl Fig. l0. That band is preferably of length such as to accommodate the number of sector-shaped sub-assemblies needed Ifor the particular magneticrstructure to be built. a Vsequence ofK channel-shaped non-magnetic metal `pieces di having vlugs 42 extending from each right-angular I edge thereof, which are hingedly connected by hinge pins d3, so that the whole constitutes a flexible linked band. 1

Thus, the sub-assembly stampings, properly assembled within the channel of theu band Il@ may be readily introduced into the assembly former or jig shown inFi'g. lli vThat'assembly jig has a frusto-conical wall 4l! ofy non-magnetic material with a `wider mouthy 45, intov which the ilexible band4 loaded with itsmultiplicity of sectorshapedsub-assemblies. A may be introduced as shown,"with the 'several sub-assemblies extending in spacedrelation'radially of the funnel. An electro-magnet made up of a core i6 and an associated coil 4l encompasses the outer part of the vformer lll andther'eby magnetically retains the sub-assemblies in radial position as shown. The car'ryingbandriill may now readily be removed without displacement of the sub-assemblies. .A plunger d8 `axially of the frusto-conical assembling former now lpresses the entire crown of sub-assemblies downward so as to bring the same into close v,contifguity at the cylindrical lower end (i9v ofthe former at which is disposed in telescoped relationv a removable strong walled mold into which the assembly is forced by the plunger, as shown. I j l In the illustrative lembodiment shown, v the blanks are vof the .typegshown in Fig. '7, so that in the assembled relation within the mold, they present an vannular groove 5lv in which is to be accommodated; the electro-magnetic coil as- Preferably the linked band comprises 4 sembly 52 that has been impregnated according to usual practice.

After introduction of that coil assembly into the structure within the mold 50, following removal of the latter from the jig 4d, the armature 53 which may be of construction similar to the laminated structure described is applied and thereupon the entire structure is impregnated to ll its voids with a thermo-setting magnetic plastic that carries iron or other magnetic particles; For this purpose the mold is enlarged in diameter as at 5d at its outer end for a bore larger than that which snugly accommodates the magnetic structure S. The connecting shoulder between the enlarged bore 54 and the magnet cylinder structure carrying bore is desirably beveled at 55 as shown. The magnetic plastic 5E which is usually about two parts of iron or other magnetic powder and one part thermosetting resin, is introduced within the mold above the cavity that houses the magnetic structure and is pressed into position by piston 51 under hydraulic pressure. In this operation the magnetic plastic lquenes, enters about the center, plug 5,8 of the mold and thence radially outward through the magnet structure to lill all of the interstices thereof and to expel the air therefrom peripherally. After the material has expanded and hardened, the plunger is withdrawn and the magnetic structure is then removed from mold 5U. The expanded and hardened plastic not only lls the interstices of the structure but also bonds it into a securely assembled unit which is para magnetic throughout its bulk, without air lspaces that detract from the reluctance thereof.

Where the notches are cut in the longitudinal edge of the strip as in Fig. 8, the electro-rriagnetic coil will of course be lodged in a peripheral groove about the cylindrical core as will be readily understood.

Where the embodiment of Fig. 6 is employed the completed magnetic structure will have an annular hollow therein determined by the Open-` ings 33. Such cylindrical structure is of course to be sawed midway between its ends to provide two magnet cores similar to that shown in Fig. 12.

Thus it will be seen that the present invention alfords a simple and inexpensive procedure for not only producing the laminations, but for expeditiously assembling them and bonding them into a unitary cylindrical construction o f minimum reluctance. There is no need for individual handling of the laminationsY in the assembly operation. By the method of the present invention the coil carrying groove in the magnetic structure results from the assembly of the previously notched or perforated laminations and there is thus avoided the danger of conductively bonding successive laminations together which would be incurred were the pre-assembled laminated core to have its coil carrying groove machined thereinto. l v

As many changes could be made in the above construction and method and many apparently widely different embodiments of'thisinvention could be made without departing from the scope of the claim, it is intended that all matter contained in the abovey description or shown in the accompanying drawings shallbe interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by. Letters Patent of the United States is:

A laminated, generally cylindrical magnet structure comprising a multiplicity. of substan- 5 tially identical generally radially arranged substantially sector-shaped sub-assemblies, each sub-assembly being made of two laminations of unequal length, the longer lamination being folded over the shorter one at the outer edge thereof, whereby the outer or peripheral portion is three ply and the inner portion is one ply and the intermediate portion is two ply.

GUSTAVE NAHMAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Kammeyer July 15, 1890 Number Number Number Name Date Berry Sept. 10, 1901 Gerding June 8, 1915 Desloge Nov. 4, 1924 Bailey Dec. 15, 1931 Howie May 16, 1933 Daley June 12, 1934 Bourvers Sept. l, 1936 Eppelsheim'er Dec. 7, 1938 Graneld May 2, 1944 Behlmer Aug. 8, 1944 Foster Sept. 26, 1944 Camilli Aug. 14, 1945 FOREIGN PATENTS Country Date Great Britain Apr. 5, 1938 

